1. Field of the Invention
The present invention relates to a hard disk drive assembly.
2. Description of Related Art
Hard disk drives contain magnetic heads which magnetize and sense the magnetic fields of adjacent magnetic disks. The introduction of contaminants such as dust or water into the drive unit may induce errors during the operation of the disk. It would be desirable to absolutely seal the disk drive to prevent foreign matter from enter the inner cavity of the drive unit. Unfortunately, defects occur in the manufacturing or subsequent use of the disk drive, such that a perfect seal is not always attained. For this reason most commercially available hard disk drives contain filter systems that remove contaminants that enter the drive unit. Such filter systems typically have a dedicated opening or openings through which ambient air may flow into the disk drive. A filter(s) is typically placed in fluid communication with the opening to capture any contaminants that may enter the drive.
A filter system for a hard disk drive must be capable of removing both dust and water particles that may enter the drive unit. Additionally, it is also desirable to have a second filter system that removes any contaminants that were not captured by the primary filters, trapped in the drive during assembly, or that enter the cavity through a secondary opening. Such a filter system must also compensate for variances in the ambient pressure. For example, using the disk drive at elevation may reduce the internal pressure within the drive unit. Subsequent use at lower altitude may cause the higher pressure ambient to force air into the disk drive. It would therefore be desirable to have a drive unit that has an efficient filter system and which does not allow air to enter the inner cavity of the disk drive when the unit is used in environments having different air pressures.